Despite the fact that complications of tetracycline therapy have been known for years and despite the warning that has been included in the "package insert" since 1970, tetracycline continues to be prescribed widely for children. Indeed, in the year ending June 1973, approximately 15 tons of tetracycline in liquid pediatric dosage forms alone were certified by the FDA. The first phase of this project was a baseline epidemiologic study of nearly 59,000 children which revealed that over 4,000 (7%) received more than 7,000 tetracycline prescriptions. Twenty-seven percent (527) of 1,947 participating physicians prescribed tetracycline: 26 physicians (5%) wrote 54% of the prescriptions for 45% of the children. Characteristics of the prescribers are detailed in the publication of the results (JAMA 237:2069-2074, May 9, 1977). Succeeding stages of the project are designed to assess strategies to influence inappropriate prescribing. After the baseline study, physician provider participants in the Medicaid program were mailed an advisory to appraise them of the dangers of inappropriate prescribing of tetracyclines. Approximately one year later the JAMA article referenced above was published along with an editorial describing proper use of the drug. Analyses of the effects of these two actions are to be undertaken. The project also will demonstrate the usefulness of claims file data for intervention and follow-up monitoring. The claims file approach is innovative and provides an inexpensive data source.